The ash clouds from Chile's Puyehue volcano are causing travel chaos across the Southern Hemisphere from South America to Australia and New Zealand, stranding thousands of passengers.
The two airports serving Argentina's capital and the main international airport in Uruguay closed again late on Sunday over safety fears sparked by the ash cloud, which has stretched over 10,000 kilometers (6,000 miles).
The Puyehue eruption, which began 10 days ago, has forced the cancellation of hundreds of flights over the past week and a half. While the problem remained localized in Chile and bordering Argentina during the first week, the cloud spread last Friday causing cancellations across South America towards Uruguay and into Brazil.
In Argentina's southern Patagonia region, the volcanic ash closed roads and schools, blanketed a ski resort, Bariloche, and turned an Andean lake a deep charcoal gray color.
U.N. Secretary General Ban Ki-Moon, in Argentina as part of a regional tour, had to travel about 300 kilometers (185 miles) by bus to get to Buenos Aires after his flight was diverted to another airport, President Cristina Fernandez said.
Over the weekend, the globetrotting ash cloud made its way over to Australia and New Zealand, grounding several international and domestic flights. The two country's airlines differed on how to react to the ash, with Qantas and Jetstar cancelling flights, while Virgin and Air New Zealand continued operations by diverting flights and altering altitudes.
The ash cloud is sitting at about 8000 meters, which is at, or close to, the cruising altitude for most passenger jet aircraft. However, the cloud was expected to drift higher later in the day, easing the threat to commercial aircraft.
Australia's Volcanic Ash Advisory Centre said flights could be affected for several days, mostly in southeast Australia, which includes Tasmania and Melbourne.
''I think it's fair to say there will be more disruption, so that's the bit of bad news. The weather patterns are breaking the ash up, but as it breaks up it's like chasing leaves around the yard,'' Dr Andrew Tupper said.
''We don't know exactly where it will go next.''
The centre is tracking a 1500-kilometre cloud stretching from Tasmania to the southern coast of South Australia; it was expected to reach Adelaide overnight.
Dr Tupper also remarked that, while the ash cloud is on its way back to South America, it will likely return to Australia on its second circuit of the globe.
It has been known to do a double lap in the past.
Back in South America, air traffic into and out of Argentina's two largest airports remained on hold Monday due to ash from the volcanic eruption in neighboring Chile, although a number of flights were scheduled for the evening pending clearance from aviation authorities.
Officials from the civil-aviation administration are set to meet at 5:00 p.m. local time (1600 EDT) to consider a lifting of the flight suspensions, a representative from the operator of both airports, Aeropuertos 2000, said.
As more ash falls were forecast later on Monday in Patagonia, retailers, farmers, fishers and transport officials will be watching the winds and praying for change.